Quote Originally Posted by PaulP View Post
Just for the record I'm running all stepper in series configurations, ie 4 wires.
Ok, this bit is a little confusing.? Are you saying the motors only have 4 wires or it's got 8 wires and your only using 4 of them.?

If it's an 8 wire motor then you have it wired wrong which would explain all your problems, in fact, if I'm correct then I'm surprised it even works.

For series or parallel, you still use all 8 wires but connected in a different order. If it's a 4 wire motor then you don't have the option to wire parallel or series because that is already determined by the factory.
Often 4 wire motors are series-wound but you can get them parallel wound but would need to ask the manufacturer to know for sure.

The problem with Series wound motors is that you need twice the amount of volts to get the same speed/torque as a parallel wound motor. For a Mill, series-wound is a good choice because higher torque is produced at lower RPM but it quickly drops away as the RPM rise which isn't good for a router. So if you do have series-wound motors then it's highly likely you don't have enough volts which is why torque is dropping away as the RPM's rise and your getting missed steps

Like Neale says the best way to wire the coils for a router is in parallel. then you would set the current to 4.2a in protune. When setting current always use the peak value.

Whta voltage are you running and what velocity and Acc do you have them tuned at.?